Can I issue an invoice without being registered?

The situation can rise easily. A person who is not registered gets the opportunity to do a little job for a couple of days. It is just some pocket money, but he is requested to issue an invoice!. Can he do that?
Obviously it is illegal to issue an invoice if the IVA(VAT), that legally needs to be added to it, is not going to be declared and pay!.
The law requires that any individual who is going to become IVA collector registers as such. Similarly, the income in the invoice will generate the obligation to file tax.

Only from this point, it is clear that some form of registration is necessary if your are going to issue an invoice.

You can find online some companies that offer you the service of issuing invoices for you without the need to be registered if you become part of a partnership. This type of companies have recently been on the spot of Social Security inspection dept and some have been closed down as illegal.

In some exceptional occasions, a person might be able to issue an invoice only registering in the Tax office and not in the social security as self-employed.
Consider the following scenario. A worker of a company who is paying social security as an employee needs to do a job for 1 day: He is invited to give a talk or impart a seminar. In this case, this is not his regular business, and he already pays Social Security. He will only need to register as IVA collector for the occasion and can issue his invoice to the event organiser.

In most cases though registering only in Tax Office will not work and can bring problems as there are other implications not considered in this article.

With the new law for autonomo workers there is a provision that can help those with little expectation of income to comply with the social security obligations.

Before introducing this change in 2018, the difficulty used to be that the legislation did not allow self employed ones to register only for a few days and pay social security accordingly. The social security contribution as self employed was, in every case, for the complete month. This made sometimes not worth-doing some small jobs in which the incomes were going to be spent virtually on social security…

However in the new law for Autonomo workers, approved since January 2018, the autonomo can sign on and off and pay contribution only for the number of days that he has been registered.

This will allow autonomos to sign off in periods when they have no work to do or during holiday time. It also make easy to take small jobs for a few days without have to pay unreasonable social security contributions.

However there is a word of caution:

This can only be done 3 times per year. After that, the autonomo would need to pay for a complete months.

This arrangement will not work if there is a bigger structure than simply a sole trader. For instances, if there are employees or other registrations, such as EORI ( for importation) , ROI ( intra-community transactions) etc… the whole thing will collapse after un-registration and all needs to be done again.